Coherent Oscillations in Chlorosome Elucidated by Two-Dimensional Electronic Spectroscopy

Jun, Sunhong; Yang, Cheolhee; Isaji, Megumi; Tamiaki, Hitoshi; Kim, Jeongho; Ihee, Hyotcherl

doi:10.1021/jz500328w

Cited by 26 publications

(43 citation statements)

References 63 publications

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“…20,182 Indeed, increased attention to the dynamical characteristics of the exciton-phonon coupling has arisen from 2D electronic spectroscopy experiments performed in recent years on several photosynthetic pigmentprotein complexes and in conjugated polymers. [183][184][185][186][187][188][189][190][191][192][193][194][195][196][197][198][199][200] These experiments have in fact unveiled unexpected long-lived quantum coherence effects in the energy migration process, an indication that EET occurs in an intermediate coupling regime. While the actual consequences of quantum coherence in the light-harvesting efficiency of these systems is still subject of a heated debate, understanding the molecular basis sustaining coherence effects have far reaching consequences, e.g.…”

Section: Spectral Densities Disorder and Correlationsmentioning

confidence: 92%

“…Often, like in the LHCII complex of plants, the large number of pigments involved make those fittings ambiguous, so other studies, especially in the last years, attempt also the prediction of site energies using the quantum-chemical methods described in Section 2. Due to the recent discovery of long-lasting quantum coherence effects in several photosynthetic complexes, 183,184,[188][189][190][191][192][193][194][195][196][197][198][199][200] which have underscored the importance of the vibrations in the energy transfer process, in the last decade some groups have also pursued the prediction of the spectral density of pigment-protein coupling from simulation (see section 4).…”

Section: Biological Light Harvesting Systemsmentioning

confidence: 99%

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Quantum Chemical Studies of Light Harvesting

2016

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The design of optimal light-harvesting (supra)molecular systems and materials is one of the most challenging frontiers of science. Theoretical methods and computational models play a fundamental role in this difficult task, as they allow the establishment of structural blueprints inspired by natural photosynthetic organisms that can be applied to the design of novel artificial light-harvesting devices. Among theoretical strategies, the application of quantum chemical tools represents an important reality that has already reached an evident degree of maturity, although it still has to show its real potentials. This Review presents an overview of the state of the art of this strategy, showing the actual fields of applicability but also indicating its current limitations, which need to be solved in future developments.

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Section: Spectral Densities Disorder and Correlationsmentioning

confidence: 92%

Section: Biological Light Harvesting Systemsmentioning

confidence: 99%

Quantum Chemical Studies of Light Harvesting

2016

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“…S1 in the Electronic Supplementary Information (ESI). 23,[40][41] Briefly, the 800 nm pulses of 50 fs duration generated from a 1-kHz regenerative amplified Ti:sapphire laser (Coherent Legend Elite seeded by Vitesse) were converted to visible wavelengths by a home-built noncollinear optical parametric amplifier (NOPA). The broadband NOPA output pulses of 720 nm centre wavelength and 80 nm bandwidth were compressed by a prism compressor.…”

Section: Two-dimensional Electronic Spectroscopymentioning

confidence: 99%

Role of thermal excitation in ultrafast energy transfer in chlorosomes revealed by two-dimensional electronic spectroscopy

Jun

Yang

Kim

et al. 2015

Phys. Chem. Chem. Phys.

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Chlorosomes are the largest light harvesting complexes in nature and consist of many bacteriochlorophyll pigments forming self-assembled J-aggregates. In this work, we use two-dimensional electronic spectroscopy (2D-ES) to investigate ultrafast dynamics of excitation energy transfer (EET) in chlorosomes and their temperature dependence. From time evolution of the measured 2D electronic spectra of chlorosomes, we directly map out the distribution of the EET rate among the manifold of exciton states in a 2D energy space. In particular, it is found that the EET rate varies gradually depending on the energies of energy-donor and energy-acceptor states. In addition, from comparative 2D-ES measurements at 77 K and room temperature, we show that the EET rate exhibits subtle dependence on both the exciton energy and temperature, demonstrating the effect of thermal excitation on the EET rate. This observation suggests that active thermal excitation at room temperature prevents the excitation trapping at low-energy states and thus promotes efficient exciton diffusion in chlorosomes at ambient temperature.

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“…The time scale of the anisotropy decay observed in this work is also in good agreement with ultrafast line shape dynamics (20-30 fs) revealed in the 2D spectra of chlorosomes using two-dimensional electronic spectroscopy. 10,13 In those studies, the fast line shape dynamics were attributed to downhill energy transfer through a ladder of exciton states of various energies. Specifically, it was suggested that such ultrafast energy redistribution of initial excitation can occur only within and/or among coherent domains in the close proximity in the same BChl layer, mainly from smaller domains (of high energies) to larger ones (of low energies).…”

Section: 5mentioning

confidence: 99%

Ultrafast Energy Transfer in Chlorosome Probed by Femtosecond Pump-Probe Polarization Anisotropy

Jun¹,

Kim²,

Yang³

et al. 2014

Bulletin of the Korean Chemical Society

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Energy transfer in photosynthetic light harvesting complexes (LHCs) has attracted much interest because of its technological potential in solar cell applications and a recent proposal that quantum coherence might play a role in achieving energy transfer of extraordinarily high efficiency.1 Among various natural photosynthetic LHCs, chlorosomes are the largest and the most efficient LHCs found in nature. 2Chlorosomes consist of bacteriochlorophyll (BChl) c, d, e, and f molecules self-assembled into supramolecular J-type aggregates without any protein, which is in contrast to other pigment-protein LHCs. This unique architecture allows us to easily synthesize chlorosomes and their chemically modified analogs, which can be used as building elements of artificial photosynthesis.3 On the other hand, the large size of chlorosome prevents the determination of its supramolecular structural organization at the molecular level, and the exact arrangement of BChl molecules in chlorosome is still in controversy with the proposed models of curved lamellar structures and/or multi-layered rolls. 4,5Pump-probe polarization anisotropy probes the time evolution of the transition dipole orientation of photoexcited molecules in real time using a pair of linearly polarized laser pulses separated by a time delay. In particular, when the measurement is performed for an ensemble of molecules, the average orientation of the transition dipoles of individual molecules is obtained. Therefore, this technique has been mainly used for measuring the rotational diffusion dynamics of molecules, but it can also effectively probe the dynamics of excitation energy transfer in multi-chromophore systems such as conjugated polymers and photosynthetic LHCs. Especially, pump-probe polarization anisotropy is one of the methods that can uniquely detect electronic coherence created among the excited states, which is considered to play an important role in efficient energy transfer of molecular aggregates, in the form of coherent oscillations superimposed on its decay. Previously, pump-probe polarization anisotropy has been applied to various types of chlorosomes. 8,9 From those studies, two major decay components were identified on the time scales of ~1 ps and ~10 ps. These kinetic components were attributed to layer-to-layer (or roll-to-roll) energy transfer and/or energy transfer from chlorosome to the baseplate. However, although it was reported that ultrafast energy transfer occurs on sub-ps time scale in chlorosomes, 9,10 any faster decay dynamics of polarization anisotropy have not been reported yet, partly due to limited time resolution (> 100 fs) of the previous studies. In this work, in order to probe the dynamics of excitation energy transfer on ultrafast time scale, we apply pump-probe polarization anisotropy to chlorosome from Chlorobaculum (Cba.) limnaeum using the laser pulses of 15 fs duration.The details of the pump-probe polarization anisotropy experiment performed at room temperature are described in the Supporting Information (SI). Figure ...

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Coherent Oscillations in Chlorosome Elucidated by Two-Dimensional Electronic Spectroscopy

Cited by 26 publications

References 63 publications

Quantum Chemical Studies of Light Harvesting

Quantum Chemical Studies of Light Harvesting

Role of thermal excitation in ultrafast energy transfer in chlorosomes revealed by two-dimensional electronic spectroscopy

Ultrafast Energy Transfer in Chlorosome Probed by Femtosecond Pump-Probe Polarization Anisotropy

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